[FFmpeg-user] convert from bt601 to bt709

[Andy Furniss]

Bob Maple wrote:
>> I think it's in an atom called ACLR;  I doubt ffmpeg writes this
>> either...
>
> So in looking at the source, ffmpeg _does_ write this Avid extension
> if the codec is DNxHD, and hard-codes it as 'RGB range' which sounds
> wrong but the Avid codecs give the right result and it looks right
> in Quicktime Player.  This was converting v210 (Uncompressed 4:2:2
> 10-bit) to DNxHD.
>
> With that said, I just did some tests from a 10-bit RGB DPX source
> to DNxHD and I can't make it right either.  The range gets re-scaled
> to 16-235 (even though it already is) and the color primaries aren't
> right... but the math for this is starting to go out of my
> territory, and trying to figure out the path through the code is
> going even further.

Recalling some tests I did in another thread, the only way I know to get
rgb -> yuv without getting the ranges changed is to use yuvj. I guess
there is another way as this gets described as depreciated, but using 
the range parameter only seems to work when doing yuv -> yuv.